A study described as “exploratory” has found that women who experience influenza (the flu) during pregnancy may increase their baby’s chance of having autism. The study, using data from Denmark, found little evidence that autism is linked to having mild, short episodes of fever, or with common minor infections during pregnancy, such as sinus infections or urinary tract infections.

However, the study did find that women who had the flu while pregnant were twice as likely to have a child who would be later diagnosed with an autism spectrum disorder (ASD). Women who had prolonged episodes of fever (a week or more) during pregnancy were three times as likely to have a child with autism.

The study authors noted that taking antibiotics during pregnancy was a “potential” risk factor for ASDs, but not a “strong” risk factor. It’s not clear if the issue is the antibiotics themselves, or if it’s just that the women who took them were just sicker.

What does this mean, what should pregnant women do, and why the heck do so many studies use data from Denmark? Let’s take a look.

Hey, Denmark, what’s the deal?

The study, published today in the journal Pediatrics, involved self-reported data from about 97,000 women in Denmark. The women were surveyed shortly after delivery, well before they knew that their children would be diagnosed with autism. The subsequent ASD diagnoses were retrieved from the Danish Psychiatric Central Register, a computerized registry which tracks, by name, both outpatient diagnoses and mental health care hospital admissions at all public and most private mental health clinics. There’s also something called the Danish Twin Registry and the Danish Medical Birth Registry. So, I’m guessing there’s no Danish equivalent of HIPAA.

Do other studies back this up?

The study authors noted that a different recent study out of Sweden found no correlation between autism and maternal flu or fever during pregnancy.

A study of 583 children published earlier this year in the Journal of Autism and Developmental Disorders found that influenza wasn’t associated with a higher autism risk, but fever was. However, that study found that women who took medication to reduce their fever were not at a higher risk.

Another smaller study (including 483 children with autism and 2,040 children without an ASD diagnosis) from Sweden found no correlation between flu or fever and autism.

Should all pregnant women immediately freak out?

No. That this doesn’t really change anything for pregnant women. The CDC already recommends that pregnant women get a flu shot. If you’re pregnant and get sick, go to the doctor.

What are experts saying right now?

“The study is really exploratory, and more research needs to be done to understand how maternal infections, as well as other risk factors, influence the risk of autism spectrum disorders,” Coleen Boyle, director of the Centers for Disease Control and Prevention’s National Center on Birth Defects and Developmental Disabilities, told USA Today. “We need to have more information to get a better sense of what’s going on here.”

“While it is very important to get an influenza shot during pregnancy, women who get the flu this winter should not worry that they have put their child at an increased risk of developing autism,” said Dr. Richard Besser, ABC News‘ chief health and medical editor.

The link shown is a correlative link, not a causative one, cautioned Dr. Shlomo Shinnar, professor of neurology, pediatrics and epidemiology and population health at Albert Einstein College of Medicine in New York. “It can be very destructive when parts of the family, both immediate and extended, ‘blame’ the mother’s mild illness that had little to do with anything for the child’s condition,” Dr. Shinnar told ABC News.

Sorry, it’s hard for me not to make light of some of this. Two of my four kids are on the spectrum, and it seems like every time I turn around, someone’s got another theory on what causes autism. It’s really hard for me to get excited about that research. Genetically speaking, the autism tree is pretty tall in our family. So I get a little more excited when researchers help me find evidence-based, best practice therapies that are actually helpful.

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